Internal combustion engines generally require the use of a crankshaft to convert linear motion to rotational motion. Several surfaces of the crankshaft having various functions require machining to ensure proper operation of the crankshaft. Typically, some of the machining processes consist of spinning the crankshaft about a longitudinal axis that defines the main bearing journal axis of the crankshaft, while at the same time utilizing rotary grinding wheels to machine several various surfaces. This process is known as machine grinding. Since a number of surfaces of the crankshaft require machine grinding, several machining steps are required to create the finished crankshaft.
The typical current machine grinding process for four cylinder engine crankshafts uses three machine grinding steps. In order to maintain a desired production rate, more than one grinding machine may be required at each machining step. The requirement of additional machines increases the overall cost by requiring the purchase and operation of additional equipment.
The first grinding step currently used, grinds the five main bearing journal surfaces and post surface of a four cylinder engine crankshaft using multiple grinding wheels on a single spindle. One grinding machine may be utilized to meet the desired production rate. However, this configuration presents limitations when multiple crankshaft designs are being machined because the changeover time to convert the grinding machine from one crankshaft designs to another is time consuming, shutting down production and increasing labor costs. In order to maintain the desired production rate, the current solution is to utilize multiple grinding machines, one machine dedicated to each crankshaft design.
The second grinding step currently used, grinds the crankshaft pin journals using a wheel grinding machine. One grinding machine will typically to meet the desired production rate.
The third machine grinding step currently used grinds the two thrust bearing surfaces, the flywheel flange surfaces, and the gear-fit wall surface; the flywheel flange surfaces consisting of the flywheel flange mating surface, the oil seal surface, and the pilot bore hub surface. This configuration presents limitations because two machines are required in order to maintain the desired production rate.
It would be desirable to provide a crankshaft grinding system for four cylinder engine crankshafts that requires only one grinding machine, at each of the three machine grinding steps, capable of obtaining the desired production rate.